(1) Field of the Invention
The present invention relates to an insulated wire such as a winding or magnet wire used as a coil or the like in electric machinery and apparatus, communicating equipment, and electronic application devices.
(2) Description of the Related Art
Windings (magnet wires) are largely grouped into baked wires and fiber or paper covered windings. FIG. 7 is a diagram showing a cross section of a conventional baked wire. In the baked wire in which synthetic enamel 1 of various kinds such as polyurethane, polyester, polyesterimide, polyamideimide, polyamide, or the like is coated and baked on a conductor 3 shown in FIG. 1, the enamel 1 on the connecting portion must be removed when wiring is to be carried out.
Conventionally, the synthetic enamel on the baked wire is often mechanically peeled, however, this is not suitable because wires used in many electronic devices are mounted with a high density, tend to be thin so that they art easily cut by mechanical stresses.
In one conventional alternative to the above method the baked wire is dipped in chemicals. This method, however, can be hazardous because a dangerous chemical process must be conducted.
One method for removing the synthetic enamel from the baked thin wire easily, without using a dangerous chemical process, uses a laser as described in, for example, Japanese patent publication (Kokoku) No. 60-98808, Japanese patent publication (Kokai) No. 62-92712, and so forth. In this method, as shown in FIG. 2, laser lights 21 arc focused by a lens 22, and are irradiated on a conventional insulated wire 23 having a conductor coated with synthetic enamel of various kinds such as polyester and the like and baked, so that the synthetic enamel of various kinds, which is an insulator, is melted and evaporated and thus removed.
By this method, an insulator of a wiring wire such as a vinyl insulated wire, a polyethylene insulated wire, or the like in which the degree of close adhesion between a conductor and an electrical insulator is not high, the insulator can be completely removed. In a baked wire in which synthetic enamel of various kinds such as polyurethane, polyester, polyesterimide, polyamideimide, polyamide, and the like are coated and baked on a conductor, however, the degree of close adhesion between the insulator and the conductor is high so that the heat generated in the insulator by the laser irradiation is flown to the conductor. Therefore, the temperature of the insulator near the interface between the conductor and the insulating coating does not rise so that a thin film of 1 .mu.m or less of the insulator remains on the surface of the conductor. This results in problems because conduction can not be effected or soldering cannot be effected.
Ultraviolet laser energy is absorbed into the insulator at a high absorption coefficient so that the thin film of the insulator does not remain, however, there are problems in that the speed for peeling the insulator is low, the running cost is high, and so forth. On the other hand, carbon dioxide laser or YAG laser generally well used in laser beam machining has low absorption coefficient so that there is the above-mentioned problem of the remainder of the thin film of the insulator.